Filter



E- L. WOOD Feb. 20, 1940.

FILTER Filed Nov. 22, 1938 [N VENTOR A TORNEY Patented Feb. 20, 1940 PATENT OF CE I m'rnn Edward L. Wood, Detroit, Mich; Application November 22, 1938, Serial Nor 241,144

This invention relates to filters'and in particular to filters constructed in the form of a helical spring which may be applied to coffee makers and elsewhere where a readily cleanable, sanitary or long livedfilter is desired or required;

The invention will be herein described in its:

novel combination with and adaption to "coffee makers of the pressure-vacuum type in which upper and lower receptacles are employed arranged to permit water from the lower receptacleto be forced by pressure into the upp r receptacle where liquid coffee is formed by infusion when coming incontact with finely ground coffee disposed in the upper receptacle from whence the saidliquid coffee is drawn by vacuum through a Cloth filters are hard to clean and become unsanitary and unsightly after being used but a comparatively few times.

Glass filters have also been provided for coii'ee I makers in the form of a glass hall or the like having aronghened surface, however, such filters have proven unsatisfactory because of breakage and because of the danger from fine particles of 1 glass which may chip therefrom and accidentally drop into liquid coffee filtered into the bottom of a coffee maker equipped therewith.

One object of the invention is to provide a filter constructed in the form of a helical spring from coiled spring wire having transversely disposed deformations spaced along at least one side thereof which become juxtaposed to the adjacent convolution of the helix formed when the said wire is coiled into the form of a helical spring whereby to provide' minute interstices through the completed helical spring. Another object of the invention is to provide a filter constructed in the form of a coil spring having interstices formed in the periphery of the said filter by notching at least oneof the juxtaposed faces of the wire'forming the said spring.

Another object of the invention is to provide a filter for coffee makers which will serve as valve means to permit water to pass from the lower receptacle to the upper rec'eptacleof the said coffee maker through the depending funnel of 4 thereof.

schem ale-"162i the said upper receptacle underpressure c'reated by steam formed in the lower receptacle and then serve as a strainer for liquid coffee formed by infusion in the upper receptacle whenthe said liquid coffee is returnedyinto the lower receptacle 5 by vacuum formed in the said lower receptacle.

Another object of the inventionis to provide a filter for coffee makers and the like constructed. in the form of a helical spring which may be easily and readily cleaned by, extending the convolutions thereof and placing the said filter under running water. M; p Anotherlobject of the invention is to provide the coiled spring type filter forcoilee percolators and the like having a closure for the top thereof adapted to be threaded into the top ofithe said filter any desired distance whereby totprovide more or lws filter. area as may be required'to regulate the rapidity with whichliquid coifee in the top receptacle of a coffee maker is permitted 2 to pass under vacuum into the lowerreceptacle Other objects of-the invention will become apparent by reference tothe following detailed ,de-

scription taken in connection with the accom-j pg panylng drawing, in which: H

Fig. i is a vertical sectional view of acoiiee maker equipped with an embodiment of the improved filter. a

Fig 2 is an enlarged detailed fragmentary sec: tional view of the improved filtering elementadjusted toprovide more filter area than the adjustment thereof shown in Fig. 1. 1

Fig. 3 is an exploded view of the particular emloodiment of the invention disclosed in Figs. 1 and 2. l l i Fig. 4 is agreatlyenlarged fragmentary view part in section and part in elevation showing the preferred formation of filter interstices by the deforming of at least one side of wire from which 40 the filter is formed and the positioning of the said deformed side thereof into juxtaposition with the adjacent convolution of thespring intowhich thewireis coiled o a l' Referring now to the drawing wherein like numerals refer to like and correspondingparts throughout the several views, the illustrative ernbodiment of the invention disclosed is shown in novel combination with respect to a pressurevacuum type coflee maker which comprises a nular washer I2 disposed therebetween to assure a perfect seal between the outside of the said spout I III of the upper receptacle l I and the inner periphery of the neck of the said lower receptacle ID. A suitable handle I3 is preferably secured to the lower receptacle l0 around the neck thereof as indicated in Fig. 1 with a washer l4 disposed therebetween.

The novel filter I5 is constructed in the general form of a helical spring preferably made from stainless steel spring wire I6 having generally transversely disposed deformations I'I formed in at least one side thereof which becomes juxtaposed to the smooth side of the adjacent convolution of the helix formed when the said spring wire I6 is coiled into a helical spring whereby to provide a plurality of minute interstices through the, periphery of the completed filter as best shown in Figs. 3 and 4. The lower convolutions of the filter I5 are preferably not deformed in the region thereof which contacts the inner periphery of the funnel-like spout II 0 of the upper receptacle II as indicated by the numeral I8 in Figs. 1 and 2. The lower end of the said filter I5 is provided with an anchorage loop l9 considerably wider than the inside diameter of the funnel-like spout III] of the upper receptacle II to admit of frictional anchorage of the bottom of the filter therein as indicated in Figs. 1 and 2.

The top of the filter is preferably formed cylindrical in shape for about one-third of its height and is tapered for its lower two-thirds of its height at a'taper slightly greater than the taper of the inside taper of the funnel-like spout IIII of the upper receptacle II to admit of engagement in the top of the said funnel-like spout III) as shown in Figs. 1 and 2.

An upper seal 20 having an upwardly disposedstem 2| provided with a knurled handle 22 formed thereon is threaded to the same pitch as the pitch to which the spring wire I6 is coiled whereby ,to admit of, turning the said upper seal 20 into the top of the said coiledspring wire I6 as shown in Figs. 1 and 2. The depth to which the upper seal 20 is turned within the coiled spring wire I 6 of the filter I5 determines the active area of the filter I5. When relatively slower filtering is desired the upper seal 20 is threaded down further into the top of the filter I5 as shown in Fig. l. liquidcoffee remains in the upper receptacle II may be regulated at will by the user of the novel filter I5.

The spring action of the said filter I5 normally maintains the convolutions of the spring wire l6 thereof tightly juxtaposed, however, whenever pressure is created in the lower receptacle I II by the formation of steam therein, the said pressure forces water from the lower receptacle I0 up into the upper receptacle I I through the stem IIIl thereof which extends the convolutions of the spring wire I8 of,the filter It vand opens up sufiicient space between the said convolutions of the spring wire I6 to admit of water passing rapidly through the filter I5 into the upper receptacle II. Thus, the filter l5 not only functions as a filter but serves as a pressure relief valve through which water under pressure from the lower receptacle I0 is admitted to the upper receptacle H. The opening up of space between the convolutions of the spring wire I6 of the filter is so slight, the area of contact between the convolutions of the said spring w'ire I6 is so small and the return action of the convolutions of the said spring wire I8 is so rapid as to substantially Thus, the length of time the eliminate any possibility of finely ground coffee placed in the upper receptacle II becoming lodged between the said convolutions of the spring wire I6 of the filter l5 and holding the said spring wire I6 apart.

In using the novel filter disclosed herein in connection with a coffee maker the lower receptacle I 0 is filled with water to a suitable level. The upper seal 20 of the filter I5 is threaded in the top thereof to the desired depth to regulate the amount of effective filter area of the filter I5 and control the rapidity with which liquid coffee from the upper receptacle Il may pass thereter in the lower receptacle I0 is brought to a boiling point whereupon pressure formed within the lower receptacle forces water therein up through the funnel-like spout H0 of the upper receptacle II and through the filter I5 which functions as a valve as hereinbefore described in detail. When substantially all of the water from the lower receptacle ID has been forced-by pressure into the upper receptacle II, heat is no longer applied to the bottom of the coffee maker and the lower receptacle I0 of the coffee maker is permitted to cool. This cooling creates a vacuum in the lower receptacle III which draws liquid coffee which has been formed by infusion in the upper receptacle ll through the interstices of the active area of the filter l5 and down the funnellike spout H0 into the lower receptacle Il.

During the passage of the liquid coffee from the upper receptacle into the lower receptacle through the filter I5, the ground coffee is drawn to the active area of the peripheral surface of the filter I5 and forms a filter mat thereon which aids materially in the functioning of the said filter l5. Obviously, the finer the coffee is ground, the more dense the filter mat formed by the ground coffee becomes and, as a result, the filtering becomes more efficient.

When all of the liquid coffee has passed from the upper'receptacle II into thelower receptacle ID, the upper receptacle II may be removed from the top of the lower receptacle I0 and the lower receptacle may be used as a pitcher from which the liquid coffee may be poured.

When cleaning thefilter l5, the upper seal 20 thereof is turned nearly out of the upper end of the said filter I5 and the filter I5 is placed under running water, and, at the same time, the convolutions of the spring wire I6 thereof are extended by simultaneously pulling on the upper knurled handle 22 of the upper seal 20 and on the anchorage loop I9 projecting from the lower end of the said filter I5 which permits all ground coffee to be flushed from the interstices of the said filter. v

Although but one embodiment of theinvention and one application thereof have been disclosed and described in detail herein, it is obvious that many changes'and modifications may be made in the size, shape, arrangement and details of the various elements of the invention without departing from the spirit thereof and it is not intended to limit the scope of the invenappended 2. A filter tor a coflee maker comprising a' hollow coil of spring wire having "the convolutions thereof tensioned in substantially abutting relationship and having a portion of cylindrical shape and another portion of conical shape to removably engage the tunnel-like spout of the coffee maker and form a suport for the remainder of the coil, a closure supported solely by said cylindrical portion, a projection on said closure by means of which it may be adjusted, and means on the coil to provide an anchor therefor.

3. A combined filter and valve for coffee makers of the character described comprising a helical wire spring in which the convolutions thereof are normally disposed in sufilcient tensional contact with each other to make the filter resiliently self-supporting, the said helical spring having interstices formed in the periphery thereof by providing spaced deformations in at least one oi! the juxtaposed faces of the wire forming the convolutions oi the helical spring, means for sealing closed the upper end of the said helical spring, and means for removably anchoring the said combined filter and valve in filtering position plugging the top of the tunnel or the upper unit of the coffee maker leaving the upper portion oi. said combined filter and valve unsupported except by the tension of the helical wire spring per se.

4. A combined filter and valve for coflee makers of the character described comprising a hellcal wire spring in which the convolutions thereof are normally disposed in sufiicient tensional contact with each other to make the filter resiliently self-supporting, the said helical spring having interstices formed in the periphery thereof by providing spaceddeiormations in at least one of the juxtaposed faces of the wire forming the convolutions of the helical spring, disc means having helical grooves in the periphery thereof for sealing closed the upper end of the said helical wire spring threadable any desired distance into the top thereof whereby to vary its active area as a filter, and means for removably anchoring the said combined filter and valve in filtering position plugging the top of the funnel of the upper unit of the. mice maker leaving the upper portion of said combined filter and valve unsupported except by the tension of the helical wire spring per se.

5. A filter tor a coffee maker comprising a hollow coil of spring wire having at least a portion of conical shape with the-convolutions thereof tensioned in substantial abutting relationship to removably engage the funnel-like spout of the coiifee maker and form a support for the remainder of the coil, the interior of said coil being substantially unobstructed throughout the major portion of its length, a closure for the large end of the coil and anchoring means extending from the small end of the said conical portion.

' EDWARD L. WOOD. 

